GCG - Artigos em revistas internacionais
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Percorrer GCG - Artigos em revistas internacionais por autor "Albardeiro, Luís"
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- Biostratigraphic and structural research of the Guedelhinha-Lançadoiras- Algaré sector of the Neves-Corvo mine region, Iberian Pyrite BeltPublication . Pereira, Zélia; Matos, João Xavier; Mendes, Márcia; Solá, A. Rita; Albardeiro, Luís; Morais, Igor; Araújo, Vítor; Pacheco, Nelson; Oliveira, José TomásABSTRACT: Based on drill hole sampling and sedimentary rock dating by palynology, the present research focuses on the palynostratigraphic events established in the key geological section of Guedelhinha-Lancadoiras-A lgare located in the Portuguese Neves-Corvo mine region, Iberian Pyrite Belt. The age data allow detailing the lithostratigraphic sequence and further understanding the complex structural setting, representing an important contribution to the geological knowledge of this sector located to the immediate WNW of the Neves-Corvo VMS deposit. The combination of the studied events allows the reconstruction of the Devonian-Carboniferous sedimentation and paleoenvironments along the Iberian Pyrite Belt. Several stratigraphic hiatuses identified in the Neves-Corvo region by the palynological record are con-firmed, mainly occurring from the mid Frasnian to mid Famennian, from the early and mid Strunian, and from the early to late Tournaisian, which were mainly coincident with the worldwide extinction events, in particular during Frasnian-Famennian and Late Devonian times. Extensional tectonics and related gravitational faults, local uplift mechanisms and intense volcanic activity could also explain the lack of palynological data and sedimentary hiatus. In this research, the importance of the late Strunian times in the Iberian Pyrite Belt (Miospore Biozone LN of the Neves Formation) is highlighted, confirming the contemporaneity of felsic volcanism, hydrothermalism, sulphide mineralization precipitation and black shale anoxic sedimentation.
- Terrestrial environmental change across the Permian-Triassic boundary in the Karoo Zambezi Basin, Mozambique: Integrating palynological, sedimentological and carbon isotope evidencePublication . Fernandes, Paulo; Pereira, Zélia; Spangenberg, J. E.; Silva Mendes, Márcia Cristina; Lopes, Gilda; Jorge, Raul C. G. Santos; Albardeiro, Luís; Font, Eric; Adatte, T.; Vennemann, T.; Marques, J.ABSTRACT: The Permian-Triassic boundary (PTB; ca. 252 Ma) marks the most severe biotic crisis in Earth history, yet high-resolution terrestrial records from southeastern Gondwana, outside the Main Karoo Basin of South Africa, remain scarce. We present a multidisciplinary investigation of borehole CIMT-014 from the N'Cond & eacute;dzi Coalfield, Mozambique, which preserves a near-continuous continental succession spanning the PTB within the Karoo Zambezi Basin. Sedimentological, palynological, palynofacies, total organic carbon (TOC), and organic carbon isotope (delta(13)Corg) analyses were integrated to reconstruct environmental, ecological, and carbon-cycle changes across the transition. The uppermost Permian Matinde Formation comprises organic-rich floodplain mudstones, siltstones, and thin coal seams deposited under warm, humid conditions and dominated by Glossopteris-associated gymnosperm floras. Crossing the PTB, these deposits are abruptly replaced by conglomeratic, lacustrine, and fluvial sediments of the C & aacute;dzi Formation. Palynological data document a marked decline of glossopterid and other gymnosperm pollen, followed by a short-lived increase in opportunistic lycophyte and fern spores. Concurrently, palynofacies shift from assemblages rich in non-opaque phytoclasts to assemblages dominated by opaque phytoclasts, while TOC values decline from >40 wt% in coal-bearing intervals to <0.2 wt% in the earliest Triassic succession. A pronounced negative delta(13)Corg excursion of approximately 5.4 parts per thousand occurs across the boundary interval, with values decreasing from -25.0 parts per thousand to a minimum of -30.4 parts per thousand. The magnitude, stratigraphic coherence, and association with floral turnover, cessation of peat formation, and fluvial reorganisation indicate that the isotopic carbon excursion records a major perturbation of the global carbon cycle rather than local diagenetic effects. The isotopic signal is consistent with widespread carbon-cycle disruption linked to Siberian Traps magmatism and associated greenhouse-gas emissions. Our results demonstrate that terrestrial ecosystems in southeastern Gondwana experienced profound ecological and environmental disruption during the end-Permian crisis and establish the Karoo Zambezi Basin of Mozambique as a key archive for correlating continental records of the PTB in Gondwana.